Shield for use with electrical appliances



B. HUGHES SHIELD FOR USE WITH ELECTRICAL APPLIANCES Dec. s, 19.27'.r

Filed sep't. 18, 1925 #l F1012 I :fumo

ITITTITT man INV ENToR Bava/:MIM HUGHES ,my ATTQRNEYS Patented De'c. 6,1927.

UNITED STATES BENJAMIN HUGHES, 0F MONTREAL, QUEBEC, CANADA.

SHIELD FOR USE WITH ELECTRICAL APPLIANCES.

Application led September 18, 1925. Serial No. 57,246.

This invention relates to new and useful improvements in shields orbarriers for use with transformers and othenelectrical appliances andthe object of the invention is to provide a shield which will prevent orstop with `the minimum amount of loss the magnetic, the static, or theelectrofmagnetic influence` lield, or wave which may be thrown out froman inductance coil, a condenser, or any electro-statically orelectro-magnetically charged body, from travelling over to anothersimilar piece of apparatus and inducing a potential in that part.

Another object is to provide a shield of the class stated which willconiine the field of an electro-static, or electro-magnetic device andisolate it so that the approach of an object of electric or magneticmaterial will not interfere with the magnetic balance or tune of suchdevices.

A further object is to provide a shield of the class stated which willprevent unneces sary losses within the shield itself.

In my invention, I provide a shield which is composed ofelectro-magnetic conducting material in combination with insulatingmaterial or matter. This shield is placed in close proximity to orbetween any electrostatically or electro-magnetically charged body orbodies to form a barrier or wall across the path of travel of theelectro-magnetic field, to cut oli or interrupt the mag* netic lines offorce which would otherwise progress to regions Where other parts may bedisturbed electrically by potential or currents being induced orinfluenced by such lines of force. p

In the drawings which. disclose many forms of my improved shield and theapplication thereof;

Figure 1 is a perspective view of a transformer with my improved shieldforming part of the casing therefor.

Figure 2 shows the application of my im proved shield in mountinginductance coils for radio apparatus.

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Figure 3 is an elevation of a shield with conductors of square crosssection embedded therein. v

Figure 1is a sectional elevation taken on the line 4 4 Figure 3.

Figure 5 is an elevation of a shield withl conductors of round crosssection embedded therein.

Figure 6 is an elevation-similar teV lFigure 3, with conductors of ovalcross section embedded therein.

Figure 7 is an elevation of a shield with strips of conducting materialembedded in insulating material.

Figure 8 is a sectional elevation taken on theline 8 8 Figure 7.

Figure 9 is a shield made in the form of a comb.

Figure 10 is a sectional elevation taken on the line 10410 Figure 9.

Figure 11 is an elevation of a shield of slotted construction.

Figure 12 is a sectional elevation taken on the line 12-12 Figure 11.

Figure 13 is an elevation of a shield provided with a plurality of rowsof conducting material embedded in insulating material.

Figure 14 is a sectional elevation taken on the line lil-14 Figure 13.

Referring more particularly to the drawings. and in particular toFigures 3 to 8 inclusive, 2() designates a piece of flat insulatingmaterial having embedded or moulded therein a plurality of metalconductors of various shapes, spaced from one another by the insulation.In Figure 3 the conductors 21 are made square and are preferably made ofthin material. In Figure 5 the conductors 22 are made circular, while inFigures 6 and 7 the conductors 23 and 24 are made from small oval piecesand long narrow strips of conducting material respectively. In Figure 9the shield is formed of a sheet 25, of conducting material having aplurality of open ended slots 26 formed `therein which form a comb-likestructure. In Figure 11 the shield is shown constructed of a sheet 27 ofconducting material having a series of parallel slots 28 formed therein.In Figure 13 a plurality of rows of dlscs 29, of any desired shape and'in layers spaced from one another maybe embedded ormoulded in a sheet30 of insulating material. Other modilications may be made in theconstruction, such as embedding particles of dust of an electricalconductive nature in a body of insulating material without departingfrom the spirit of the invention. The shield material may be made inlong strips and out to suit the requirements of the user.

In Figure 1 atransformer 31 is shown, provided with a shield 32constructed 1n a similar manner to the construction shown in Figure 10.The shield is placed asshown,

that is, at right angles to the magnetic lines of force emanating byinductance from the transformer and shown by the arrows 33. In Figure 2,the shield 34, is placed between the inductance coils 35 and which maybe mounted in any desired manner on a panel 36. It will be readilyunderstood that the uses of such a shield are many and varied as thedevice may be used as an enclosure for certain electrical equipment, orpanels for radio devices, as part of a tuning condenser or to form awall, partition or barrier placed in any position to preventinterference between any electro-statically or electro-magneticallycharged bodies, devices, material or matter.

ln operation a shield of the class described when placed in the form ofa sheet or a wall across the path of travel of an electro-magnetic fieldwill act in a three-fold manner. l. The magneticallyv conductiveparticles which may be made of iron, nickel, cobalt, or any alloyscontaining such metals or materials will by reason of their magneticpropf erties conduct the magnetic component o the field along throughthemselves and send it back by a shorter and easier path to the source,thereby interrupting or cutting off the magnetic lines of force andpreventing same from travelling past the shield.

2. The electro-static component of the vfield will be conducted to theimmediate region surrounding each of the conductive particles because oftheir electric conductive nature and will be so distributed between the.conductive and non-conductive matter of the shield that the potential ofthe eld will be confined to the shield and may, if desired, be broughtto earth potential by connecting a conductive piece of material from theconductive portions of the shield to earth as shown in Figures 9 and 11,so that an electro-magnetic field or wave interrupted by a wall orshield of this nature, will be divided into its component parts andbrought under control, and may be carried off or dispersed as desired,instead of progressing to regions where other parts may be disturbedelectrically by potentlal or currents induced in such parts.

3. The third advantage of using such an arrangement of material inshield construction is of great importance, that is the prevention ofunnecessary losses within the `shield itself. This losstakes place inthe form of eddy currents. When a continuous.

body of metal is used to interrupt an electro-magnetic lield of varyingintensity, eddy currents .submerged within the metal will be set up andthe path of such currents will tend to be at right angles to the linesof magnetic force. These eddy currents absorb energy and result in adefinite loss, whereas a shield as herein described and which is made upof alternate conductive and nonconductive substances or matter acts as abarrier to the progress of an electro-magnetic field and at the sametime prevents the llow of such eddyor loss currents within the body, byreason of the discontinuity of the conducting material through which theeddy currents flow, thereby dispersing the field at a minimum loss.

Having thus described my invention, what l claim is l. A. shield of thecharacter described comprising a series of fiat metal elements embeddedin a mass of insulating material,- the elements of said series beingcontained in a common plane in edge to edge relation with each elementcompletely enveloped and isolated from the remaining elements bysurrounding portions of the insulating material. y

2. A shield of the character described comprising spaced parallel seriesof flat metal elements imbedded in a mass of insulating material withthe elements of each ser1es contained in a common plane in edge to edgerelation, each of said elements being completely enveloped and isolatedfrom the remaining elements by surrounding portions of the insulatingmaterial.

3. A shield as recited in claim 2 in which the elements of one seriesare staggered with respect to the elements of the adjacent scr1es.

ln witness whereof, I have hereunto set my hand..

BENJAMIN HUGHES.

